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A003719
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Expansion of tan(x)*cosh(x).
(Formerly M3996)
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4
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1, 5, 41, 685, 19921, 887765, 56126201, 4776869245, 526589630881, 72989204937125, 12424192360405961, 2547879762929443405, 619570064016825283441, 176273806836039238900085, 58010159408189457446855321, 21864887814006548202566779165
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OFFSET
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0,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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a(n) ~ cosh(Pi/2) * (2*n+1)! * 2^(2*n+3) / Pi^(2*n+2). -Vaclav Kotesovec,Feb 16 2015
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MATHEMATICA
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nn = 20; Table[(CoefficientList[Series[Cosh[x]*Tan[x], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (*Vaclav Kotesovec,Feb 16 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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